Water Pump Selection Guide

There are many important factors that you must consider before buying a water pump so that it meets all your requirements. Some of these factors are as follows:

1. Flow Rate:

The flow rate of a water pump determines the amount of water that can be pumped over a specific period of time. It is measured as the number of liters per min i.e. l/min.

If you are planning to buy the water pump for commercial use like at farms or job sites, you must buy a model that can pump over 2,500 liters of water per minute. However, if you want to use at your home or garden, you can buy a pump offering a flow rate between 100 – 200 liters per minute.

2. Pump Horsepower:

Horsepower drives the motor to operate the water pump. If the horsepower is more, this means that the volume (flow) and the pressure (PSI) will be more too.

It helps in getting the work done quickly and is very helpful while moving water to a longer distance.

For a regular house pump that can be used at home, it should offer 0.5 HP to 2 HP.

3. Pressure:

The pressure of the water pump is measured in bars. The pressure is the force with which the water is being pumped. Generally, to raise the water at a height of 10 meters, a force of one bar i.e. 14.5 PSI is required.

One thing that you must remember is pressure and flow rate are always proportional to each other.

4. Vertical Suction Lift:

Vertical suction lift means the vertical distance between the water source and the water pump. To be more precise, if the water pump is mounted at the top of the well, the vertical suction will be calculated as the distance between the pump and the water level.

The higher you set up the pump, the higher suction lift you will require.

5. Maximum Head Lift:

The maximum head lift is the total height at which the water pump can pump the water from the water source to the tank or its final destination. For example, if you are buying a water pump with a maximum head of 50 meters and if you are trying to pump water in levels higher than 50 meters, the flow rate will be zero.

Hence, the type of pump that you are going to buy should have a maximum head lift that is higher than the height that you are planning to pump the water.

6. Size of the Inlet:

The size of the inlet valve has a huge impact on the total time required to pump out the water. If the size of the inlet valve is big, it will be able to pump out more amount of water in lesser time. Thus, it offers double benefits – helps in saving time and gets the job done quickly.

The size of the inlet valve generally ranges between 1 inch to 6 inches. However, some water pumps have water inlets more than 6 inches too.

Note:

You should always try and match the size of the hose with your existing pipes to allow easy connection while installing the water pump.

7. Priming:

Priming is a process where the air is removed from the pump and the suction line. Priming can be done either manually or automatically.

If you are doing it manually, you will have to first fill the pump with water and then turn on the machine. A few models of water pumps come equipped with its self-priming technology. In these models, you can simply plug in the switch and turn on the motor. These models are the most suitable usage at home.

8. Diameter:

You must also consider the diameter and check if it is going to fit well in the shaft of the borewell.

You should check the actual dimension of the shaft of the well accurately and then leave a little space for improper specifications or issues. This way, you will know that the water pump will fit properly to the shaft of the well.

9. Foot Valves:

A foot valve is quite similar to a check valve. It allows only one-way flow and shuts off whenever the water flow is coming in a reverse direction. Foot valves are very helpful in preventing the water inside the pipe and the storage tank from flowing back to the ground and keep the pump primed.

These valves fit perfectly over the pick-up end of the water pipe.

10. Water Pump Material:

The design and the materials used to make the water pump are one of the most important factors that determine the longevity and reliability of the pump.

While checking the quality of the pump, you must check the materials that are used to make parts like the shaft, the impeller, the engine casing, the pump housing, and other fittings.

  • Cast Iron Pumps:

Cast iron is one of the most commonly used housing materials, especially in electric pumps.

The impellers can be made using either cast iron or bronze.

Nevertheless, cast iron housings along with bronze impellers are considered as a great and cost-effective combination.

  • Stainless Steel Pumps:

Stainless steel is resistant to corrosion. Hence, most of the electrically powered high centrifugal pumps, sump pumps, and submersible pumps are usually made using stainless steel housings and driver hardware.

  • Bronze Pumps:

Out of all the common materials used for housing and impeller that you will find in most of the electric-powered water pumps, bronze (i.e. an alloy of tin and copper) offers an amazing combination of cost and resistance to corrosion, abrasion, and cavitation.

Water pumps made using bronze are great to be used in seawater and warm water environments.

  • Aluminum Pumps:

Aluminum is a lightweight material (it is almost one-third of the weight of steel). Thus, it is easy to cast and provides good durability. It is resistant to corrosion too. Aluminum pumps are generally used at places that require portable pumps to perform tougher tasks.

11. Single-stage or Multi-stage Pumps:

Water pumps can be either single-stage or multi-stage.

Single-stage models feature only one impeller that sucks and pumps the water. Multi-stage models, on the other hand, feature multiple impellers.

The advantage of using a multi-stage pump is that there is a progressive increase in the water pressure by each impeller. These pumps offer great hydraulic efficiency. Not only these models are robust but are cost-effective too. Because of the way they operate, multi-stage pumps are often called as centrifugal pumps where the water is sucked in because of the high-speed rotation of the impeller.

12. Single-phase or Multi-phase Power Supply:

Different models of water pumps have different levels of power. It depends on their specific features. While some models use a single-phase power supply, others use a three-phase power supply.

13. Thermal Overload Protection:

Thermal overload protection in the water pump helps in reducing the risks of short circuits, especially when the pump is running dry.

14. Noise:

You might also want to consider the number of decibels that the water pump generates, depending on where and how are you installing the pump. This is not applicable for submersible water pumps though.

15. Quality of the Pump:

You should always check the quality of the pump. The crucial parts like engine or motor should be from a good and reputed brand as they offer a long lifespan. This is very helpful in maintaining the quality of the water pump for a long time.

16. Price:

You can buy a good water pump within a price range of Rs. 2,000 to Rs. 5,000. It is advised to invest in branded machines so that it provides years of service.

17. Warranty:

Checking the warranty period is very important, especially in products like water pumps that are designed for robust use. You should always go with a brand that offers a warranty for a minimum of 1 year. Some brands even offer a replacement policy if there is any major issue. Hence, go through the return and replacement policy properly.

Types of water pumps

There are 2 types of water pumps namely domestic pumps and agricultural pumps. Let us learn about them in detail.

1. Domestic Pumps

As the name suggests, the domestic pumps are used for domestic usage such as daily water consumption. These pumps usually offer a lower flow rate and work on low power when compared to the agricultural pumps. The domestic pumps are further divided into 5 categories. Let’s check them out!

  • Self-Prime Regenerative Pumps

The Self-prime regenerative pumps are used for handling freshwater that is free from chemicals or any abrasive materials. They are built using self-priming technology and thus, they do not require a foot valve.

These pumps have vanes on either side of the rim that rotate continuously inside the pump’s casing. Instead of the fluid getting discharged from the top, it is re-circulated back to the bottom of the impeller. This helps the pump in re-priming itself. These types of pumps are best suitable for domestic water supply or at gardens or lawns.

  • Centrifugal Pumps

Like the self-prime regenerative pumps, the Centrifugal Pumps are best suitable for handling freshwater that is free from chemical or abrasive materials and can be used for filling water in swimming pools, or in gardens, small irrigation farms, etc.

When compared to regenerative pumps, these pumps offer higher discharge and excellent hydraulic performance. They operate efficiently at a very low maintenance cost. The main feature of these pumps is they circulate the water by converting rotational kinetic energy into hydrodynamic energy. They derive this rotational energy using the electric motor and use centrifugal force to pump out the water.

  • Submersible Pumps

The submersible pumps come is sealed motors and they are installed inside the water bodies such as wells or bore wells. These types of pumps do not require priming and provide a higher efficiency rate.

The submersible pumps are considered as a wise choice for domestic usage as they are low-maintenance pumps and once you install it, you will not have to worry about anything.

  • Bore Well Compressor Pumps

The Bore Well Compressor Pumps are designed specially to pump water from deep bore wells. These pumps use the air pressure to lift the water and are best suited for wells with a depth of 600 ft. There are 2 types of borewell compressor pumps – monobloc and belt-driven.

  • Pressure Booster Pumps

The Pressure Booster Pumps are generally used in residential areas to provide smooth and pressurized freshwater supply. They are engineered to provide the required pressure according to your requirements.

These pumps are usually installed at places with deep and shallow water supplies to promote pressurized water flow.

2. Agricultural Pumps

Agricultural pumps are used by farmers to promote good crop production. They are even used at commercial places where the expected flow rate is higher. There are 2 types of agricultural pumps.

  • Centrifugal Monoblock Pumps

These pumps function in a similar way as the centrifugal pumps. The monoblock pumps use centrifugal force to pump out the water but the only difference here is they are used to cover larger areas. Thus, these pumps are more efficient and provide a higher flow rate that can be up to 25lps.

  • Submersible Pumps

The agricultural submersible pumps also work the same way by keeping the priming issue aside. They offer a higher power of 60 hp and can be operated at the depth of 1640 feet. These pumps provide a higher flow rate that can range up to 38lps.

Frequently Asked Questions

1. How can I calculate the size of the water pump that I should buy?

There are two important factors that can be helpful in deciding the size of the water pump: motor power and maximum head lift.
If you are buying a water pump for household purposes, you can opt for a model with 0.5HP to 2HP.
Before buying a water pump, don’t forget to check the maximum head life. It is usually mentioned in feet. The maximum head life is the total height at which the pump can start pumping water from the water source to the destination.
Generally, you must select a water pump that has a maximum head that is more than the height at which you want to pump the water.

2. For a height of 60 feet, which water pump is the best?

It is always good to buy a pump that has a maximum head life more than the required height. Some of our suggestions are Kirloskar Chotu Water Motor Pump and Sameer Water Pump

3. Why do you need a water pump?

A water pump is a very essential tool and can be used for multiple purposes such as:
*Irrigation purpose for agricultural land
*Lawn sprinkling
*At construction sites
*Draining or filling the swimming pool or pond
*Draining water from a basement
*Draining flooded areas

4. What is a monoblock pump?

Monoblock pumps are those where the rotating parts of the pump are placed on a standard shaft. This type of placement helps in providing a dynamic balance to the rotating parts, which, in turn, causes less vibration and noise while functioning.

5. Why does a pump start to lose its prime?

Since we use water pumps on a daily basis, the possibilities are high that they might lose efficiency, if not maintained properly. Some of the major reasons are as follows:
*Leakage on the pump’s base-valve or shaft-seal.
*When there is a blockage caused in its suction-strainer due to debris.

6. What is Suction Cavitation?

A suction-cavitation occurs whenever a pump is in under-low pressure or high vacuum conditions. During this process, bubbles or cavities start forming at the eye of the impeller. 

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